Edgar Guest’s poem from “The Secret of the Ages, by Robert Collier, [1926]”

You can do as much as you think you can,
But you’ll never accomplish more;
If you’re afraid of yourself, young man,
There’s little for you in store.
For failure comes from the inside first,
It’s there, if we only knew it,
And you can win, though you face the worst,
If you feel that you’re going to do it.